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This is a hard difficulty System Design question, commonly asked during Onsite rounds at Meta.

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This question is commonly asked for Software Engineer candidates at Meta during technical interviews.

Design a product notifications system | Meta Interview Question

Quick Overview

This question evaluates system design competencies for building a large-scale notifications platform—covering architecture, APIs, data modeling, event pipelines, delivery semantics (retries, deduplication, idempotency), targeting/segmentation, localization, monitoring, and legal compliance such as GDPR/CCPA.

System Design: Push Notifications and In‑App Messaging Platform

Context

Design a notifications platform for a large consumer mobile app with millions of daily active users. The platform must support both push notifications (iOS/Android) and in‑app messaging, with rich targeting, personalization, and compliance.

Functional Requirements

User preferences and consent
- Channels: push, in‑app (future‑proof for email/SMS)
- Topics/categories, frequency caps
- Quiet hours and time zone handling
Segmentation and targeting
- Dynamic segments, real‑time triggers, and scheduled campaigns
Deduplication
- Across retries and overlapping campaigns; vendor collapse keys
Rate limiting and throttling
- Per user, per campaign, and global/vendor limits
Retries, backoff, and idempotency
Scheduling and batching
- Future send times and batching for efficiency
A/B experiments
- Randomized assignment, holdouts, metrics
Localization
- Templates, placeholders, pluralization, fallbacks
In‑app messaging
- Message inbox, triggers, display rules, and impression tracking

System Requirements

Describe APIs, data model, event pipeline, delivery workers
Integrate with APNs (iOS) and FCM (Android)
Scale to millions of DAUs and bursty traffic
Multi‑region deployment and CAP trade‑offs
Monitoring, alerting, and SLOs
GDPR/CCPA compliance
Failure handling and graceful degradation
Capacity estimates and a safe rollout plan

Quick Overview

Functional Requirements

User preferences and consent

Channels: push, in‑app (future‑proof for email/SMS)
Topics/categories, frequency caps
Quiet hours and time zone handling

Segmentation and targeting

Dynamic segments, real‑time triggers, and scheduled campaigns

Deduplication

Across retries and overlapping campaigns; vendor collapse keys

Rate limiting and throttling

Per user, per campaign, and global/vendor limits

Retries, backoff, and idempotency

Scheduling and batching

Future send times and batching for efficiency

A/B experiments

Randomized assignment, holdouts, metrics

Localization

Templates, placeholders, pluralization, fallbacks

In‑app messaging

Message inbox, triggers, display rules, and impression tracking

System Requirements

Describe APIs, data model, event pipeline, delivery workers

Integrate with APNs (iOS) and FCM (Android)

Scale to millions of DAUs and bursty traffic

Multi‑region deployment and CAP trade‑offs

Monitoring, alerting, and SLOs

GDPR/CCPA compliance

Failure handling and graceful degradation

Capacity estimates and a safe rollout plan

Design a product notifications system

Quick Overview

System Design: Push Notifications and In‑App Messaging Platform

Context

Functional Requirements

System Requirements

Solution

Submit Your Answer to Earn 20XP

Design a product notifications system

Quick Overview

System Design: Push Notifications and In‑App Messaging Platform

Context

Functional Requirements

System Requirements

Solution

Submit Your Answer to Earn 20XP